buysbal {pastecs} | R Documentation

## Buys-Ballot table

### Description

Calculate a Buys-Ballot table from a time-series

### Usage

    buysbal(x, y=NULL, frequency=12, units="years", datemin=NULL,
            dateformat="m/d/Y", count=FALSE)

### Arguments

`x` | Either a vector with time values (in this case, `y` must be defined), or a regular time-series
`y` | If `x` is a vector with time values, `y` must contain corresponding observations
`frequency` | The frequency of observations per year to use in the Buys-Ballot table. By default `frequency=12` which corresponds to monthly samples, and the resulting table has 12 column, one per month
`units` | either `"years"` (by default), and time is not rescaled, or `"days"`, and the time is rescaled to "years" with the function `daystoyears()`
`datemin` | A character string representing the first date, using a format corresponding to `dateformat`. For instance, with `datemin="04/23/1998"` and `dateformat="m/d/Y"`, the first observation is assumed to be made the 23th April 1998. In R, it can also be a POSIXt date (see `?DataTimeClasses`). In this case, `dateformat` is not required and is ignored. By default, `datemin=NULL`
`dateformat` | The format used for the date in `datemin`. For instance, `"d/m/Y"` or `"m/d/Y"` (by default). The distinction between "Y" and "y" is not important in Splus, but it is vital in R to use "y" for two-digit years (ex: 89) and "Y" for four-digits years (ex: 1989), or the date will not be correctly converted! In R, you can also use a POSIXt format specification like "%d-%m%Y" for instance (see `?strptime` for a complete description of POSIXt format specification. In both Splus and R, you can also use "mon" for abbreviated months like "mon d Y" for "Apr 20 1965", and "month" for fully-spelled months like "d month Y" for "24 September 2003"
`count` | If `FALSE` (by default), the Buys-Ballot table is calculated. If `TRUE`, the function returns only the number of observations that are used in each cell of the Buys-Ballot table

### Details

A Buys-Ballot table summarizes data to highlight seasonal variations. Each line is one year and each column is a period of the year (12 months, 4 quarters, 52 weeks,...). A cell ij of this table contain the mean value for all observations made during the year i at the period j.

### Value

A matrix containing either the Buys-Ballot table (`count=FALSE`), or the number of observations used to build the table (`count=TRUE`)

### Author(s)

Frédéric Ibanez (ibanez@obs-vlfr.fr), Philippe Grosjean (phgrosjean@sciviews.org)

### See Also

`daystoyears`, `tsd`

### Examples

    data(releve)
    buysbal(releve$Day, releve$Melosul, frequency=4, units="days",
            datemin="21/03/1989", dateformat="d/m/Y")
    buysbal(releve$Day, releve$Melosul, frequency=4, units="days",
            datemin="21/03/1989", dateformat="d/m/Y", count=TRUE)

[Package pastecs version 1.3-2 Index]